JP2006325073A - Image inputting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce a static image of relatively high resolution using a thinning image. <P>SOLUTION: When setting a photographing mode, a thinning reading is sequentially performed from an image sensor 4 by a driving signal of a timing control unit 9. The image that has been read is temporarily stored in a memory 7 in units of first to fourth frames. The thinned image of each frame is read from the memory 7 and displayed on a display device 11 sequentially as a through-image. For each of the first to fourth frames, a thinning rate is 2/4 while offset values in row direction and column direction of pixels for starting thinning are (0, 0), (0, 2), (2, 0), and (2, 2). When a release is operated at an operation means 10, the images of first to fourth frames are composited to generate an image of high resolution with no thinning. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image input apparatus capable of performing thinning processing and reading out from an image sensor.

  For example, in an image input device such as a digital still camera, generally, a through image for monitoring a shooting angle can always be displayed on an image display device such as an LCD, and a user can release a still image while monitoring the through image. It is acquired by performing.

A still image is usually required to be a high-resolution image, while a through-image for a monitor displays an image in real time with a limit on the size of the LCD mounted on the camera (a limit on the number of pixels). In general, a low-resolution image is used because of the restriction of the processing time for the image processing. Therefore, at the time of capturing a through image, the image data subjected to the thinning process is read from the image sensor (see Patent Document 1).
JP 2002-320235 A

  However, when capturing a through image for monitoring, pixel data that has been subjected to thinning processing is read out from the image sensor, and a release operation is performed in the imaging operation for still images (reading without thinning processing). Will start after. Accordingly, there is a time difference between the image at the time of monitoring and the image at the time when the still image is actually shot, and a still image at the moment when the photographer intends to shoot cannot generally be obtained.

  An object of the present invention is to provide an image input apparatus that can reproduce a relatively high-resolution still image using a thinned image.

  An image input apparatus according to the present invention temporarily holds an image sensor, image data reading means for performing decimation readout for sequentially different pixels in a plurality of frames from the image sensor, and a decimation image obtained in the plurality of frames. It is characterized by comprising a memory and a synthesized image generating means for synthesizing the thinned images obtained in a plurality of frames and generating a synthesized image having a larger number of pixels than the thinned images of each frame.

  Each image obtained in a plurality of frames is sequentially displayed as a through image, for example, and the composite image generating means is activated when the release button is operated.

  The thinning rate in a plurality of frames is held as thinning information, for example, and thinning out reading of each frame is performed based on this thinning rate. Further, the decimation offset values in a plurality of frames are held as decimation information, for example, and decimation readout of each frame is performed based on the offset values.

  Further, the number of pixels of the composite image corresponds to, for example, the number of effective pixels of the image sensor.

  As described above, according to the present invention, it is possible to provide an image input device that can reproduce a relatively high-resolution still image using a thinned image.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating an electrical configuration of an image input apparatus according to an embodiment of the present invention. In the present embodiment, the image input apparatus is, for example, a digital still camera.

  The digital still camera of this embodiment includes a lens (lens system) 1, a shutter 3, and an image sensor (imaging device) 4, and a subject image is formed on the imaging surface of the image sensor 4 via the lens 1. The exposure is controlled by a shutter 3 whose opening / closing operation is controlled by a shutter drive mechanism 2. Instead of the shutter 3, an electronic shutter operation of the image sensor itself may be used.

  The driving of the image sensor 4 is controlled by a drive signal from the timing control unit 9, and the timing control unit 9 is controlled by the system control unit 8. The subject image converted into an electrical signal in the image sensor 4 is read as an analog image signal, for example, and converted into a digital image signal via an AD converter (ADC) 5.

  The digital image signal is then input to the digital signal processing unit 6, and the digital image signal input to the digital signal processing unit 6 is temporarily stored in the memory 7 as image data after being subjected to predetermined image signal processing. Is done.

  The image data stored in the memory 7 can be displayed on a display device 11 such as an LCD via the system control unit 8 and can be recorded on an external storage device 12 such as a memory card. It can be transferred to an external device such as a personal computer, a printer, or a TV monitor.

  The system control unit 8 controls the entire digital still camera, and is also connected to the shutter drive mechanism 2, the AD converter 5, the digital signal processing unit 6, and the like, and also controls these units. Further, the system control unit 8 is connected to an operation unit (input unit) 10, and the user operates the operation unit 10 to send a signal command to the system control unit 8, so that the operation of the digital still camera and various types of operations are performed. It can be used for mode setting and various parameter setting.

  In the present embodiment, for example, a Bayer-array CMOS circuit is employed as the image sensor 4, but it goes without saying that it may be a CCD or the like. FIG. 2 is a diagram schematically showing the configuration of the image sensor 4 used in the present embodiment.

  Each pixel of the CMOS image sensor 4 is connected to a row selection circuit 3A and a column selection circuit 3B as is well known in the art, and the row selection circuit 3A and the column selection circuit 3B are connected to a timing control unit 9. ing. That is, reading of image data from the image sensor 4 is performed by controlling output on / off for each pixel of m rows and n columns based on the drive pulse from the timing control unit 9.

  In FIG. 2, when the thinning rate in the row direction and the column direction is 2/4 and the offset is 2 pixels, that is, 2 pixels are thinned out every 4 pixels in the vertical and horizontal directions, and the thinning start position is changed from the lower left pixel to the horizontal right The case where it is offset by 2 pixels each in the vertical direction and the vertical direction is illustrated. In FIG. 2, pixels that are not thinned out are indicated by hatching, and pixels that are thinned out are indicated by white.

  Thinning information used for thinning readout is held in the timing control unit 9 as row thinning information and column thinning information, and is held, for example, as a thinning rate and an offset value in the row direction and the column direction. The row thinning information and the column thinning information are sent from the system control unit 8 to the storage unit 14 such as a register of the timing control unit 9 based on the setting of the thinning mode by the user or a preset value.

  In the present embodiment, as shown in FIGS. 3 to 6, different pixels are thinned out for each frame. For example, in this embodiment, since the thinning rate is 2/4 in both the row direction and the column direction, as shown in FIGS. 3 to 6, the thinning pattern is divided into four patterns and is different for each of the four frames. Thinning is performed on the pixels.

  That is, the thinning out in the first to fourth frames is the first frame (see FIG. 3) in which the lower left 4 pixels are read out in units of 4 × 4 pixels (16 pixels in total) including RGB pixels, and the lower right 4 The second frame from which pixels are read (see FIG. 4), the third frame from which the upper left four pixels are read (see FIG. 5), and the fourth frame from which the upper right four pixels are read (see FIG. 6) are sequentially read.

  At this time, as described above, in the first to fourth frames, the thinning rate in the row direction and the column direction is 2/4. In the first frame, the offset in the row direction and the column direction is 0 pixel, and in the second frame, the offset in the row direction is 2 pixels and the offset in the column direction is 0 pixel. In the third frame, the offset in the row direction is 0 pixel and the offset in the column direction is 2 pixels. In the fourth frame, the offset is 2 pixels in both the row direction and the column direction. The row thinning and column thinning information is set in the storage unit 14 of the timing control unit 9 by the system control unit 8.

  The thinned images read for each of the first to fourth frames are temporarily held in the memory 7 via the digital signal processing unit 6 and are sequentially displayed on the display device 11 as a through image, for example. If the release button (one of the operation means 10) is operated during this period, the images of the first to fourth frames shown in FIGS. 3 to 6 are combined, and as shown in FIG. One image that has not been generated is generated.

  That is, row thinning information and column thinning information are stored in the storage unit 16 of the digital signal processing unit 6 in the same manner as the storage unit 14, and in the data synthesis unit 15 of the digital signal processing unit 6 based on these pieces of information. The thinned images (first to fourth frames) stored in the memory 7 are combined to reproduce one high-definition image corresponding to the number of pixels of the image sensor 4 without thinning.

  Next, the imaging operation in the present embodiment will be described with reference to the flowchart of FIG.

  For example, when the digital still camera is set to the photographing mode, each register in the timing control unit 9 is set in step S101. That is, the frame period, horizontal period, exposure time, sensor timing, etc. are set.

  Next, in step S102, the thinning information in the row direction and the column direction in the storage units 14 and 16, that is, the thinning rate and the offset value in the row direction and the column direction are set. In this embodiment, the thinning rate in the row direction and the column direction is set to 2/4, and the offset value is set to 0 pixel as an initial value in both the row direction and the column direction.

  In step S103, the shutter drive mechanism 2 and the image sensor 4 are controlled based on the set values, and the image pickup operation in the image sensor 4 is started. That is, in step S104, the thinned image of the first frame is initially read (FIG. 3).

  In step S105, it is determined whether or not the release button has been operated. If not, it is determined in step S106 whether or not the current frame is the first frame. If it is determined in step S106 that the current frame is the first frame, the row direction offset value is set to 0 pixels and the column direction offset value is set to 2 pixels in step S107, and the process returns to step S104 to return to the second frame. Reading is started (FIG. 4).

  On the other hand, if it is determined in step S106 that the current frame is not the first frame, it is determined in step S108 whether or not the current frame is the second frame. If it is determined in step S108 that the current frame is the second frame, the row direction offset value is set to 2 pixels and the column direction offset value is set to 0 pixel in step S109. Then, returning to step S104, reading of the third frame is started (FIG. 5).

  If it is determined in step S108 that the current frame is not the second frame, it is determined in step S110 whether or not the current frame is the third frame. If it is determined in step S110 that the current frame is the third frame, in step S111, the row direction offset value is set to 2 pixels and the column direction offset value is set to 2 pixels, and then the process returns to step S104 to return to the fourth frame. Reading of the frame is started (FIG. 6).

  Furthermore, if it is determined in step S110 that the current frame is not the third frame, both the row direction and column direction offset values are set to 0 pixels in step S112, and the process returns to step S104 to read the first frame. It starts again (FIG. 3). Thereafter, the same processing is repeated until the release button is pressed, and the newly read thinned image is stored in the area corresponding to the first to fourth frames of the memory 7 and is sequentially displayed as a through image on the display device 11. Is displayed.

  On the other hand, if it is determined in step S105 that the release button has been operated, the process proceeds to step S113, where the latest consecutive thinned out images of the first to fourth frames are combined to generate an image without thinning (FIG. 7). ) Is generated. The combined undecimated image is then displayed on the display device 11 and recorded, for example, in the external storage device 12 or the like. Since each frame image is acquired in an extremely short time as compared with human movement, each image of the first to fourth frames is already acquired when the user presses the release button.

  As described above, according to the present embodiment, a fixed pixel is not a thinning target as in the conventional thinning process, and a different pixel is a thinning target in each frame. By synthesizing the images, it is possible to generate an image with relatively high accuracy. As a result, it is possible to acquire a high-definition still image when the release button is operated substantially, and it is possible to maintain a resolution equivalent to the number of image sensor pixels. Also, since each frame image is thinned, the frame rate can be improved.

  In the present embodiment, the thinning rate 2/4 has been described as an example. However, the thinning rate is arbitrary, and the number of frames corresponding to each thinning is not limited to four frames. In this embodiment, thinning is performed in the row direction and the column direction. However, the present embodiment is also applicable to the case where thinning is performed in only one direction.

  In the present embodiment, the composite image has been exemplified by the image sensor pixel count, but for example, an intermediate resolution image between the frame image and the image sensor pixel count using only some frames. Can also be generated.

  Further, in the present embodiment, in reading each frame, there are no pixels that are redundantly read, but some pixels may be redundantly read in a plurality of frames.

It is a block diagram which shows the structure of the digital still camera which is one Embodiment to which this invention was applied. It is a figure which shows typically the structure of the CMOS type image sensor used by this embodiment. It is a schematic diagram which shows the state of thinning out of the first frame. It is a schematic diagram which shows the state of thinning out the second frame. It is a schematic diagram which shows the state of thinning out of the third frame. It is a schematic diagram which shows the state of thinning out of the fourth frame. It is a schematic diagram of the synthesized image which synthesize | combined the 1st-4th frame. It is a flowchart which shows the procedure of the imaging operation in this embodiment.

Explanation of symbols

4 Image sensor 6 Digital signal processing unit 7 Memory 8 System control unit 9 Timing control unit 10 Operating means 11 Display device 12 External storage device

Claims (6)

An image sensor;
Image data reading means for performing thinning-out reading for different pixels sequentially in a plurality of frames from the imaging device;
A memory that temporarily holds a thinned image obtained in the plurality of frames;
An image input apparatus, comprising: a combined image generating unit configured to combine the thinned images obtained in the plurality of frames to generate a combined image having a larger number of pixels than the thinned images of the frames.   The image input device according to claim 1, wherein each image obtained in the plurality of frames is sequentially displayed as a through image.   The image input apparatus according to claim 1, wherein the composite image generation unit is activated when a release button is operated.   2. The image input apparatus according to claim 1, wherein thinning rates in the plurality of frames are held as thinning information, and thinning-out reading of each frame is performed based on the thinning rates.   2. The image input apparatus according to claim 1, wherein thinning offset values in the plurality of frames are respectively held as thinning information, and thinning out reading of each frame is performed based on the offset values. The image input device according to claim 1, wherein the number of pixels of the composite image corresponds to the number of effective pixels of the image sensor.

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